Watch escapement



p 8, 1954 F. SMITH 2,690,048

WATCH ESCAPEMENT Filed Feb. 2, 1953 2 shee'ts'fiheet 1 Fig Cecil F. Smith INVENTOR.

Sept. 28, 1954 Filed Feb. 2 1953 C. F. SMITH WATCH ESCAPEMENT 2 Sheets-Sheet 2 Cecil F. Smith INVENTOR.

Patented Sept. 28, 1954 UNITED STATES TENT OFFICE WATCH ESCAPEMENT Cecil F. Smith, Greenville, Miss.

Application February 2, 1953, Serial No. 334,617

8 Claims. 1

This invention relates to escapement elements of watch and clock movements and has for its particular object the increase of the timekeeping accuracy of clocks and watches.

The intermittent impulses to an escapement wheel is effected in the conventional watch movements by the engagement and disengagement of the peripheral teeth of the escapement wheel with spaced pallet stones carried by an oscillating pallet fork. When the teeth contact the pallet stones they strike the pallet stones to cause angular oscillation of the pallet fork. The construction of this invention therefore features means for-controlling the angular movement of the pallet fork while also enabling each of the pallet stones to deliver an impulse adapted to provide an optimum amount of energy to the pallet fork.

Still further objects of this invention reside in the provision of an escapement mechanism that is strong and durable, highly eflicient in operation, capable of being readily installed on various existing timepieces, and which may be readily substituted for conventional escape mechanisms in order to insure better timekeeping by the timepieces.

These, together with the various ancillary objects of the invention which will become apparent as the following description proceeds, are attained by this escapement mechanism, a preferred embodiment of which has been illustrated in the accompanying drawings, by way of example only, wherein:

Figure l is a plan view of the escapement mechanism, with the fork being shown in part in section for greater detail, the escapement mechanism being in an initial stage of a cycle of operation;

Figures 2 through 4 are views similar to that of Figure 1 but showing the escapement mechanism in successive stages of operation; and,

Figure 5 is a sectional view through a timepiece showing the escapement mechanism in elevation.

With continuing reference to the accompanying drawings wherein like reference numerals designate similar parts throughout the various views, it will be seen that the various elements forming the novel combination include certain elements which are conventional. These include the spaced tines l0 and I2 formed with cam surfaces 14 and I6 respectively, which are adapted to cooperate with a roller jewel I8 which projects rigidly and perpendicularly from a disc roller 2t. The disc roller is mounted on the staff 22 of a balance wheel (not shown).

In accordance with the concept of the present invention the conventional tines l0 and 12 are mounted on a fork arm 24 of the pallet fork 25 which carries pallet stones 28 and 30, the pallet stones 28 and 30 being vertically offset from each other. Eccentrically mounted banking stops or pins 32 and 34 are provided for limiting the oscillatory movement of the pallet fork 26 when the pallet arm 24 engages the banking stops 32 and 34. A substantially U-shaped locking memher having a central connecting portion 36 interconnecting locking arms 38 and 40 is secured to the upper surface of the pallet fork 26. The locking arm 38 is substantially triangular in shape but the locking arm 40 is provided with a crescent shape portion 42. The pallet stones 228 and 30 are provided with teeth engaging beveled portions 44 and 46.

An escapement wheel 48 having a hub 5% secured to a shaft 52 driven by the main spring is provided with upper and lower rows of teeth as indicated at 54 and 56 respectively. The main spring 52 is shown schematically as being at 55 but as is more conventional, if desired, the escapement wheel 48 may be driven by gearing connected to the main spring. Spaced on the upper periphery of the wheel 48 are locking lugs 58 which are adapted to be successively engaged by the locking arms 38 and 40. The pallet stone 28 is adapted to successively engage the teeth 56 of the upper row of teeth while the pallet stone 3% is adapted to engage the teeth 54 of the lower row thereof.

The successive steps of operation of this watch escapement can be best understood by successive references to Figures 1 through 4 of the drawings. With initial reference to Figures 1, it will be seen that herein the pallet fork 26 is positioned with the locking arm 38 engaging one of the locking lugs 58. This holds the fork against the banking pin 32. The pallet stone 28 is in position so that the tooth designated 56a is in position to deliver the next impulse. There is provided a safety clearance indicated at A between the pallet stone 30 and the adjacent lower tooth 5M. This prevents accidental engagement. Further, this tooth 54a has delivered the last impulse to the oscillating pallet fork 26. There is provided the distance in angular measurement marked B as the distance that the tooth 56a will travel prior to contact with the pallet stone 28 thus providing substantial momentum for delivery of energy to the pallet fork 26.

Referring now to Figure 2, it will be seen that in this state of the cycle the tooth 56a is delivering energy to the pallet stone 28 after the locking arm 38 has become disengaged from the locking lug 58 upon actuation by the jewel pin H3. The instant the locking arm 38 becomes disengaged 3 with the locking lug 58 the tooth 56a moves until it strikes the stone 28. This movement continues until the tooth 56a slides off the pallet stone 28 and travels the distance indicated A.

Referring now to Figure 3 it will be seen that in this view the escape mechanism is locked by the crescent surface 42 engaging one of the locking lugs 58. The impulse stone 3G is about to be contacted by the tooth 54b. The crescent shaped locking surface 42 engaging the lug 58 will cause the pallet arm 24 to be held against the banking pin 34.

Referring now to Figure 4 it will be seen that in this final portion of the cycle the escape wheel is delivering an impulse to the pallet stone 3!). This was made possible by the action of the jewel pin 18 due to its rotation. This movement will continue until the tooth 54b travels the distance A after it has slid out of engagement with the pallet stone 30. At that time, the locking arm 38 will engage the next locking lug. This will complete a cycle.

Since from the foregoing, the construction and advantages of this watch escapement are readily apparent, further description is believed to be unnecessary.

However, since numerous modifications will readily occur to those skilled in the art after a consideration of the foregoing specification and accompanying drawings, it is not intended to limit the invention to the precise embodiment shown and described, but all suitable modifications and equivalents may be readily resorted to that fall within the scope of the appended claims.

What is claimed as new is as follows:

1. An escapement mechanism for timepiece movements comprising a mainspring driven .escape wheel, upper and lower rows of teeth on periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a pair of locking arms carried by said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs.

2. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a pair of locking arms carried by said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs, said locking lugs extending about the periphery of said escape wheel in spaced relationship.

3. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a pair of locking arms carried by said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs, said pallet stones being offset from each other, one of said pallet stones engaging the teeth of said upper row of teeth, the other of said pallet stones engaging the teeth of said lower row of teeth.

4. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth. a pair of locking arms carried by said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs, said pallet stones being offset from each other, one of said pallet stones engaging the teeth of said upper row of teeth, the other of said pallet stones engaging the teeth of said lower row of teeth, said looking lugs extending about the periphery of said escape wheel in spaced relationship.

5. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a substantially U-shaped locking member including a pair of outwardly extending locking arms interconnected by a central connecting portion, said central connecting portion being secured to said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs.

6. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a substantially U- shaped locking member including a pair of outwardly extending locking arms interconnected by a central connecting portion, said central connecting portion being secured to said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs, said locking lugs extending about the periphery of said escape wheel in spaced relationship.

7. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the periphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a substantially U- shaped locking member including a pair of outwardly extending locking arms interconnected by a central connecting portion, said central connecting portion being secured to said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs, said pallet stones being offset from each other, one of said pallet stones engaging the teeth of said upper row of teeth, the other of said pallet stones engaging the teeth of said lower row of teeth.

8. An escapement mechanism for timepiece movements comprising a mainspring driven escape wheel, upper and lower rows of teeth on the eriphery of said escape wheel, a pallet fork, pallet stones carried by said pallet fork successively engaging said teeth, a substantially U- shaped locking member including a pair of outwardly extending locking arms interconnected by a central connecting portion, said central connecting portion being secured to said pallet fork, locking lugs on said escape wheel, said locking arms successively engaging said locking lugs, said pallet stones being oifset from each other, one of said pallet stones engaging the teeth of said upper row of teeth, the other of said pallet stones engaging the teeth of said lower row of teeth, said locking lugs extending about the periphery of said escape wheel in spaced relationship.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 194,744 Thomson Aug. 28, 1877 1,343,798 Toda June 15, 1920 

